Mick McCarthy was surprised by the way his team defended as they crashed to the heaviest defeat of his 68 games in charge against Russia today.
It was the first time a Republic of Ireland team had conceded four goals since losing 4-1 to Denmark in a 1985 World Cup qualifier.
"It's been a bad day at the office for us in terms of defending," admitted McCarthy.
"That's not us. We don't start like that normally. We usually go forward and play at a high tempo to pen them in.
"I'm disappointed with the goals we've conceded. We don't normally concede goals like that.
"We came here to try to win the game and we believed we could but we gave a poor goal away and suddenly found ourselves two down.
"After that we were taking chances and chasing the game but we had to do that. I would sooner sit here having lost 4-2 and given it a good go than not give it a go."
Gary Doherty and Clinton Morrison scored Ireland's goals but McCarthy acknowledged that his men couldn't hope to get away with bad defending.
"We've scored two goals and I wouldn't expect to do that away from home and get beaten under normal circumstances.
"But there's nothing we can do about it now. We have to concentrate on our next game.
"It's now about motivation for all of us and winning that game at home (against Switzerland in October)."
Steve Finnan was guilty of some slack marking in the 20th minute as Andrei Kariaka cut inside him before coolly slipping the ball past Shay Given.
And Ireland were 2-0 down in the 25th minute when Vladimir Beschastnykn swept home his 26th international goal.
Substitute Doherty - who is playing in defence for Tottenham this season - took on Niall Quinn's mantle of super-sub when he pulled a goal back after 68 minutes,
Russia restored their two-goal advantage a minute later when Alexander Kerzhakov scored with a diving header.
Birmingham's Clinton Morrison, who had replaced Duff, ensured a tense finale as he pulled a second goal back for the Irish.
But Irish hopes of a draw were snuffed out five minutes from time by a Phil Babb own goal seconds after coming off the bench.
Russian manager Valeri Gazzaev was delighted with his team's performance.
"This is a very big win for us because in the last few years Ireland have lost only one or two matches," he said.
Both managers singled out Robbie Keane for praise.
Gazzaev added: "Keane is a good player and caused us many problems.
And McCarthy said: "Robbie was excellent, he was first class all night."
PA